Thanks for the pictures and video JO .
The car seems like it is running very well and strong 
11 Likes
Questions JO, #1 how much space between the lower part of the gasifier bottom and top of the grate do you have now?
#2 What is the distance between the the lower nozzles and the grate?
#3 What is the distance between the upper and lower nozzles is 6" , how high are the upper nozzles from the top of the grate Now?
What Wayne said the Volvo sounds good running down the road. Yes once the charcoal bed is settled in a and ash cone is reestablshed, then you will know for sure. Thanks for the video, I love driving in Sweden even if it is on video.
12 Likes
So, thousand pound trailer full of wood behind and you’ll be in heart of Europe in blink of an eye. 
10 Likes
Kamil, if only I could take my time and make it a full week project to get down there, drive small backroads and stay away from forign police. That would be lots of fun.
10 Likes
JO, I’m glad you’re back “in the saddle” and with fire under your “hooves”, it looks like it’s working well. I can only cite my experience with supplying air to the “forbidden” area:
- when starting with a stick, I thicken the charcoal in the lower part, so there is no fear that air will remain, which would mix with the gas
- when it warms up a little, a glowing pulp forms below, which represents minimal resistance, all the oxygen is consumed here and the charcoal disappears into ashes
- a lot of moist caloric pyrolysis gases are produced above, which prevent metals from overheating and are converted into clean gas below
- this mode enables stable operation at low load for a practically unlimited time and also good power at full load, this can be compared with a double gasoline carburetor, but of course the nozzles must be adapted to the size of the hot zone
I know you already know all this, well, it seemed to me that you doubted success a bit, and I feel “responsible”… 
13 Likes
Thanks Bob. Meassurenents as follows…
Bottom to grate about 5"
Grate to restriction top 4"
Restriction top to lower nozzles 4"
Lower nozzles to upper 6"
So, that means 14" from grate to upper nozzles.
11 Likes
And…thanks to Dr Wayne and Dr Tone.
Btw Tone, I was actually never out of the saddle 
I’ve been DOWing the Mazda truck every day. Just procastinating about fixing the Volvo, because of the colder than usual winter we’ve had.
Also, no worries about responsiblity. As you can see from my meassurenents I didn’t quite follow your lead 
I added my charcoal burner still well above the restriction. A few more miles still, until I can tell if I gained anything.
13 Likes
I did a little comparing on the measurements on my and your firetubes. You now have a 4.5" restriction opening now I think?
Correction: you put it back to 4".
And I put your lower nozzles in my drawing.
I noticed we both have 14" from the upper nozzles to the grate. I think it will be very interesting when you get yours all tune up.
14 Likes
Nice to see your Volvo is up and running again JO, it will be very interesting to hear if there is a difference after you have put some miles behind you, everything else is the same so this is a rare opportunity to tell if there is a difference.
Very nice drawings Bob and with the comparison side by side. It is not that far off from my firetube as it now takes shape, the biggest difference is the diameter as I have 10”, otherwise it i very similar surprisingly enough (to me 
), happy to see that I am not too far off.
4” top plate to upper 9 nozzles, 14” upper nozzles to grate, 9 1/2” upper nozzles to restriction, 6” upper nozzles to lower 3 nozzles (closed for now), 4 1/2” restriction to grate.
13 Likes
Bob, what Johan said. That’s a great comparing drawing.
As for my restriction, I actually put my 4" insert back in - I think last summer. I think I may have made some tary fumes with the 4.5" - 5" one. Also, I put it on 5" tall cone pedistal to try make the oxidation zone smaller, but I could tell no difference in performance. For some reason this gasifier seems to behave the same no matter what I do - except running out of fuel
BUT - to tell you the thruth - I shouldn’t complain actually. This rig runs sweat, with more power than any of my previous builds. It’s just that it’s a bit annoying in stop-and-go traffic with the hesitations during accellerations - and when it recovers and back to full power a few seconds later, it’s time to hit the brakes again
Looking good, Johan. I like the size of your nozzles. If my theory is correct, it will serve the same purpose as my lower row.
11 Likes
Okay sorry, I do have one more question. The hesitation you talk about and experiencing. If you pull up to a stop sign, and then take off from a stop right a way. Do you get this hesitation in the lost power in exceleration or is it after you are idling there for a few minutes? Long question, right?
The reason I ask is this. If my charbed gets to tight or what we call constipated, i will experience a hesitation in exceleration. My thinking is I have only a 1" clearance between the top of my grate to the bottom of my gasifier, my holes in my grate are smaller then other grates I have looked at. I also run at a higher vaccum most of the time than other WK Gasifiers. This is only when my gasifier is actively hot, not when it is cold with air pulling through the grate to the engine. This is how I know it is at my grate area and not else where like the filter or cooling tubes. Vaccum is low when gasifier is cold.
9 Likes
Bob, unfortunately even only motorbraking to slow down for an intersection or even coasting down a hill will cause hesitation if I start pulling hard on the gasifier again.
After a full stop I have rich gas/great power accellerating 1st and 2nd gear (stored gas), but about the time I shift to 3rd gear hesitation occurs. That’s when gas, which is produced during the sudden hard pull, enters the motor. About 5 more seconds of pulling hard, the gasifier recovers again.
If I accellerate carefully and gradually the there’s no noticable hesitation.
I agree about the vacuum ratio - if I for some reason have lower than usual vacuum ratio / coarse charbed, the hesitation sympthomes are less noticable. This has lead me to belive I could benefit from having lower nozzles - to introduce some oxygen down low, which a really coarse charbed does automaticly.
Yes, the charbed’s resistance is very much temperature dependent. With a dead cold charbed the vacuum ratio is close to 1:1. With the charbed lit and asking low to medium power I may see 3:1. Pulling hard for 10-15 seconds and really heat things up, the ratio is suddenly 5:1. Giving it some slack for another 15s, and I’m back to 3:1.
I hope my typing makes at least some sense
13 Likes
JO, forgive me if I write in your dark, but I will try to explain the hesitation:
- when the engine works for a while with high power, the hot zone heats up well and a lot of tar gases and water vapor are produced above
- suddenly we reduce the gas consumption and the engine works with minimum power, there is still a lot of heat in the gasifier, which allows pyrolysis to proceed, the resulting moist gases press down into the hot zone and begin to cool it quickly, thus producing very caloric gas and the engine can flood, if no more air is added
- the flow of fresh air stops in the meantime (if we have a built-in non-return valve), smoke may also appear in the air intake, because there are a lot of gases
- the engine slowly sucks these gases through the restriction opening, and the hot zone cools down quickly because there is not enough air blowing above, the pressure difference between the inside and the outside is very small
- we suddenly increase the gas intake, a vacuum is created inside the gasifier, air starts to flow through the nozzles and blows the embers, well, it takes time for everything to heat up again, and meanwhile the gas is very bad
Possible solutions to reduce these symptoms:
- extraction of humid gases (Joni)
- intensive cooling of the condensation zone
- installation of an air supply in the area of negative pressure near the restriction opening, thus preserving the glowing layer of charcoal, which kills the tar and partially radiates upwards to maintain relatively high temperatures
I don’t know the ideal solution
11 Likes
Good explanation Tone.
Just one minor thing - I don’t think I’ve ever experienced positive pressure as long as the motor is turning. If I’ve pulled really hard for a longer period of time and suddenly go to idle it seems there’s momentarely some excess heat that can take care of the steam and convert it into very rich, almost nitrogen free gas.
On the other hand, going in the other direction from idle to full power, there will suddenly be a lot of steam created in the oxidation process, but for a little while not enough heat to convert much of it to H2.
Edit: I read your explanation over again and I realise we’re describing the same thing
11 Likes
I think the lowering of your grate to create more charcoal reserve below the restriction 4" opening is a good idea. This gives more distance for the gases to go through. The temperature at the top of my grate is around 1360 f° or 737.8 C° to 1700 f° or 926.7 C° this depends on how hard I am pulling on the gasifier.
My thinking is this, the hot lobe 2000 f° or 1093.3 C° plus temperature of intense heat moves up and down in the firetube. The restriction opening is where the highest velocity of air/gases are moving just passed this point it slows down helping to keep the hot lobe above it, but it can work farther down. If it makes it to the grate the gasifier can go into heater mode. Gases may start to get burn up, less good rich gases to the engine.
In a cross over section to the drop box this temperature is probably over 900 f° or 482.2 C° plus? for the heater mode to start? I am not sure because I do not measure my temperature there.
The point is once you are at this point of the lobe close to the grate, it takes a while for it to move back up to the upper nozzles area because of the stored heat. You can see this in a fire pit. Next to the glowing charcoal, black hot charcoal no air moving over it, appy air from a leaf blower and the charcoal lights up fast to bright yellow/white hot that was yellow/orange in color, but it takes a little longer for the black charcoal to do this. Pull the air away and the charcoal stays glowing under the charcoal top pieces, they cool faster. Stored heat underneath drawing air in.
JO, once all the ash gets established into the ash cone and sealed, I hope it will be a improvement.
5 Likes
One more possible solution: 2 inches of insulation. Al Frick’s 1998 Ranger seems to take off from a stop very well. https://forum.driveonwood.com/t/wood-gas-a-98-ranger-questions/3334/41
Rindert
12 Likes
I know the hesitation all too well… had terible simptoms on preety much every raw wood vehicle.
You guys described it perfectly, not much more to add. The only way l made it work was Rocket fuel, charcoal bits will slow the convection currents and block radiation so the hopper stays cooler thus emits less steam when down to an idle.
Only mechanical thing l can think of is increasing the lengh between nozzles and hopper cone. A longer, narrow throat wuld hold less volume of wood above the glowzone, so less pirolisis. But that wuld be a real tall gasifier, less practical… and it wuld decrease moisture collection
14 Likes
Good morning Tone ,JO Kristijan and Bob.
I know I have hesitation but not enough to worry about .
Below is an old video . The first part is level road then a down hill small slope.
12 Likes
Yes KristijanL.
Tall narrow and skinny is done much in the stationary power woodgas systems.
Some evolving out to too tall. Too narrow. Too skinny. Then the users fight upper systems tar capping blockages.
Add shakers resulting in lower char bed packing. Then add more aggressive grate actions. Never quite understanding they are creating most of their problems.
I have learned to manage with just-in-time extreme wood drying. More moderate dimensioned, and batch volumes of wood feed in. All very possible on have much space stationary systems if you include the engines and generators heads heats for the fuel wood conditioning.
Roof top and open bed storage of fuel wood sacks is a performance no-no to me.
I do read and watch Tone’s now lower air jets systems and thoughts with others now using with great interest.
Steve unruh
12 Likes
Two sayings come to mind - there’s a first time for everything and - just when you think you know it all
This morning going to work both my vacuum guages showed the same super high reading. First thought was to reach for the gasifier air inlet lever, only to dicover it was already in the open position. Next - stop to crawl under the car to check the tennisball - nothing wrong - open position. I was already late and I shut down and continued on gasoline. I tried a few more times on my way, but no luck.
This is what my gasifier air inlet looked like inside this evening. The camera didn’t manage to show it all, but a tary crust completely blocked the pipe. To clean it out was relativly easy. But how did this happen? Tary smoke can sometimes back out the inlet at shutdown if the tennisball doesn’t seal properly, but I have never experienced this kind of blockage ???
9 Likes